JP2001064968A - Pile foundation structure in building - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively absorb and reflect the vibration of an earthquake or traffic, effectively scatter excessive gap water produced by the vibration and secure stable ground by winding a foaming resin board on the side face of a pile body to form a surface layer, and providing a slit along the long axial direction of the pile on the wall face side of the outer periphery of the foaming resin board. SOLUTION: A foaming resin board 3 providing one or more slits 6 is wound on one part of the pile side of a pile body 2 comprising a reinforcing bar 4 and concrete 5 to form a surface layer. In addition, the slit 6 is covered by a clogging prevention body 7, and soil and sand are prevented from entering the slit 6. Thereby vibration and impact produced by an earthquake, traffic or the like can be alleviated by the foaming resin board 3. In addition, underground water produced during a normal time is drained to the lower part of the pile through the slit 6 of the foaming resin board 3, and in the case where excessive gap water occurs instantly, the foaming resin board 3 is compressed and deformed by the slit 6 to scatter and drain water from a gap produced between the foaming resin board 3 and a soil wall to a ground direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention can be applied to improve the seismic resistance and seismic isolation of buildings, such as earthquakes and traffic vibrations, as well as countermeasures against liquefaction of the ground, and to improve the strength of piles. The present invention relates to a pile foundation structure in a building capable of doing the same.

[0002]

2. Description of the Related Art Conventionally, when building a building on a high-rise building or soft ground, a pile foundation structure such as a ready-made pile or a cast-in-place pile is used.

However, in order to improve the seismic resistance of a building by using ready-made piles, cast-in-place piles, etc., it is necessary to increase the number of piles to be constructed or use piles having a large outer diameter, which is difficult to construct. In many cases. In addition, there is a problem that the piles cannot be sufficiently supported because the piles cause vibration pollution and the piles are damaged when the piles are driven.

As a countermeasure against liquefaction of the ground in a building, a granular material such as gravel is applied to the periphery of a pile using a cement-based material or an adhesive to form a porous water-permeable layer. The upper part of the permeable layer is in contact with the gravel mat provided at the bottom of the building, and the excess pore water is drained to the ground from the permeable layer through the gravel mat (Japanese Patent Application No. Hei 8-1).
No. 54912) is disclosed.

[0005] However, in the case of a countermeasure against liquefaction of the ground in a building in which a porous permeable layer is formed on the outer periphery of the pile,
Even if a porous material is used as the water permeable layer, the effect of draining excess pore water generated instantaneously in the ground during an earthquake and not sufficiently preventing liquefaction could not be obtained.

[0006] Further, as a measure for reinforcing the building against earthquakes, a buffer layer made of a foamed resin plate such as expanded polystyrene is provided on the side of the pile. There is a construction method in which the buffer layer is compressed to reduce the deformation of the pile (Japanese Patent Application No. 9-285940).

However, in the case of a seismic retrofitting method in which a cushion layer made of expanded polystyrene or the like is provided on the side of the pile, expanded polystyrene or the like is a resin having poor resilience to compressive deformation. Water pressure causes deformation (bubbles do not return to the original position), and after construction, the buffer layer is compressed and deformed due to the displacement of the stratum due to the earthquake, mitigating the deformation of the pile body and preventing damage However, it was not possible to obtain the effect sufficiently. Further, the buffer layer was not provided with a means for draining excess pore water generated instantaneously in the ground during an earthquake, and was not able to sufficiently obtain the effect of preventing liquefaction.

[Problems to be solved by the invention]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and in a pile foundation structure of a building, vibrations of an earthquake or traffic are efficiently absorbed and reflected, and an excess gap generated by the vibrations is provided. An object of the present invention is to provide a pile foundation structure in a building capable of efficiently dispersing water, reducing drainage and pressure, and maintaining a stable ground.

[0009]

According to the present invention, there is provided (1) a pile foundation structure for a building, wherein a foamed resin disk is wound on at least a part of a side surface of a pile to form a surface layer, and On the outer wall surface side of the board, at least one
The pile foundation structure in a building having the above slit, (2) The building according to the above (1), wherein the slit on the outer peripheral wall side of the foamed resin board is covered with a clogging prevention body. (3) The pile in the building according to the above (1) or (2), which comprises one or more of a foamed polypropylene disc, a crosslinked foamed polyethylene disc, a foamed polycarbonate disc, and a foamed polyester disc as the foamed resin disc. (4) Pile foundation structure in the building according to any one of (1) to (3) above, wherein the foamed resin board has a compressive strength of 5.0 to 50.0 t / m ^2. It is.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an example in which the reinforcing structure of the present invention is applied to a pile foundation structure in a building. FIG. 2A is a vertical sectional view of a substantially partially cut-away portion of a foundation in a building. FIG. 2B is a schematic cross-sectional view taken along the line XY of FIG. FIG. 7C is an enlarged view of a main part B of FIG.

In order to provide the pile foundation reinforcement structure 1 of the present invention,
As shown in FIG. 1B, for example, at least a part of the pile side surface of the pile body 2 including the reinforcing bar 4 and the concrete 5 (FIG.
In (a), a foamed resin disc 3 having one or more slits 6 is wound around the entire side surface of the pile body to form a surface layer. In addition, the slit 6 is covered with a clogging prevention body 7 (for example, cloth (including nonwoven fabric), tape, film, rubber, or the like) to prevent earth and sand and concrete from entering the slit 6. 8 is a soft ground, and 9 is a supporting ground. By the foamed resin plate 3 forming the surface layer, it is possible to reduce vibrations and impacts caused by earthquakes, traffic, and the like.

[0012] The groundwater generated during normal times is drained to the lower part of the pile through the slit 6 of the foamed resin board 3, which is effective for hardening the ground. On the other hand, when an excessive pore water is instantaneously generated due to the pressure applied to the periphery of the pile body 2 at the time of an abnormality such as an earthquake, the foamed resin plate 3 is efficiently compressed and deformed due to the presence of the slit 6 and the foamed resin plate 3 A gap is formed between the wall surfaces (soil walls) of the holes, and a large amount of excess pore water can be dispersed and drained from the gap toward the ground, which is extremely effective for liquefaction countermeasures. The deformation of the pile 2 can be effectively prevented by the elasticity (spring) effect due to the deformation of the pile 2. Furthermore, the air layer formed in the slits 3 can effectively block vibrations and shock waves generated by an earthquake, traffic, or the like. When the foamed resin board 3 is restored after the compression deformation, the gap between the foamed resin board 3 and the wall surface (earth wall) of the hole can be eliminated, and the support strength of the pile can be improved.

The foamed resin board 3 used in the present invention has a required compressive strength, good resilience, good elongation,
Further, any material having alkali resistance (because earth and sand in the ground is alkaline) may be used, and examples thereof include foamed polypropylene, crosslinked foamed polyethylene, foamed polycarbonate, and foamed polyester. The compressive strength of the foamed resin board 3 varies depending on the structure of the building, but is 5.0 to 50.0 t.
/ M ² is preferred. Further, the foamed resin disc 3 has a small Poisson's ratio, which is preferable for seismic resistance and seismic isolation measures.

The foamed resin plate 3 has at least one slit along the longitudinal direction (FIG. 3A). When the foamed resin board 3 is bent on the surface opposite to the surface having the slit 6, the slit 6 is widened and the groove 10 is formed (FIG. 3).
(B)). The thickness of the foam resin plate 3 is 1.0 to 10.0 c.
m, and the depth D of the slit is 0.5 to 9.0 cm.
Slit 6 formed when bending foam resin board 3
The length L of the top g and the top h is 1 to 10 mm (FIG. 1).
(C)). In addition, it is preferable that the slits of the foamed resin disc 3 are equally spaced because the foamed resin disc 3 wound on a cast-in-place cast-iron cage, which will be described later, is stretched into a perfect circle when cast into concrete. .

The foamed resin disc 3 can be formed in a multilayer structure formed by laminating two or more foamed resin discs. In general, by providing layers having different characteristic impedances (density × propagation velocity) on a propagation medium (propagation ground) for vibration waves, vibration waves transmitted from a layer having a small characteristic impedance to a layer having a large characteristic impedance are transferred to a boundary surface thereof. And the transmitted energy can be reduced. In particular, when there is a slit that forms an air layer in the middle of the propagation ground, vibration waves transmitted through the ground can be effectively blocked. FIG. 2 shows an example in which a foamed resin disc is formed by laminating two different foamed resin discs 3a and 3b. FIG.
1 is a schematic sectional view of a foundation portion of a building. FIG. 2B is a schematic cross-sectional view taken along the line XY of FIG. That is, the foamed resin board 3b is wound around the side surface of the pile body 2, and the foamed resin board 3a is wound around the outer side surface of the foamed resin board 3b. Utilizing the characteristics described above, the foamed resin board 3a,
By configuring each material so that the characteristic impedance increases in the order of the foamed resin board 3b, the vibration waves transmitted from the periphery of the pile 2 are reflected at the boundary surface between the foamed resin board 3a and the foamed resin board 3b, respectively. As a result, the transmitted energy can be greatly reduced.

Next, the construction method of the present invention will be specifically described step by step. FIG. 4 and FIG. 5 are explanatory diagrams for constructing the pile foundation structure in the building of the present invention.

(1) Assemble the cage-shaped cast-in-place pile steel cage 11 by combining the main reinforcement 12, the band reinforcement 13 and the spacer 14 according to the size of the pile to be cast (FIG. 4).
(A)). Usually, the configuration of the cast-in-place pile reinforced cage 11 is 7
A length of up to 8 m is defined as one unit, and the unit is appropriately connected depending on the length of the pile to be cast. At this time, it is preferable that the main bars 12 and the band bars 13 be firmly connected to the concrete by using different diameter bars. The spacer 14 is obtained by bending a flat bar. When the cast-in-place pile steel cage 11 is inserted into the excavated hole, the spacer 14 is attached to the main reinforcement 12 and the band reinforcement 1.
A space (cover thickness) is formed between the ground 3 and the ground.
This is to prevent the strip 13 from corroding. The cover thickness is preferably about 100 to 200 mm.

(2) A foam resin board mounting ring 15 for supporting the lower end of the foam resin board 3 is provided outside the spacer 14 of the cast-in-place pile steel cage 11 (FIG. 4B).
(D)). FIG. 4D is an enlarged view of a main part A of FIG. 4C.

(3) The foamed resin board 3 is wound around the cast-in-place pile steel cage 11 such that the surface having the slit 6 covered with the clogging prevention body 7 is on the outer peripheral wall side. The lower end is fixed to the foamed resin board mounting ring 15. Also,
If necessary, the cast-in-place pile steel cage 11 on which the foamed resin board 3 is wound is inserted into the hole 16 and the foamed resin board 3
The foam resin plate 3 is fixed so as not to spread or float with a string, a band, a wire, or the like near the upper end portion (FIG. 4 (c)).

(4) Investigate the ground on which the pile is to be driven, analyze the vibration data of the earthquake or traffic, etc., and determine the optimal length and diameter of the pile body and the size and thickness of the foam resin disk 3 at the location. Now, determine the compressive strength.

(5) Holes 16 corresponding to the length, size, etc. of the pile 2 and the foamed resin board 3 are excavated at the above locations (FIG. 5 (a)). The size of the hole 16 can be appropriately changed as needed.

(6) A casing 17 is provided so that soil and the like at the opening of the excavated hole 16 do not collapse (FIG. 5).
(B)).

(7) Although not shown, the ground is strengthened by injecting and filling the bentonite liquid into the holes 16.

(8) The cast-in-place pile steel cage 11 on which the foamed resin board 3 is wound, processed in (3), is inserted into the hole 16 and built. At this time, care should be taken not to roughen the wall surface of the hole 16 (FIG. 5C).

(9) In order to prevent concrete and bentonite liquid from mixing inside the cast-in-place pile steel cage 11 surrounded by the foam resin board 3, a tremy tube is inserted to the lower part of the hole 16 and the hole is passed through the tremy tube. Concrete is cast from the lower center of 16. The foamed resin platen 3 is extended by the concrete placing pressure injected into the cast-in-place pile reinforced cage 11 and closely adheres to the wall surface of the hole 16.

(10) After removing the casing and curing, the footing 18 of the building is placed (FIG. 5).
(D)).

By applying the pile foundation structure of the building of the present invention to the pile foundation structure, the vibration or vibration of the traffic is mitigated by the foamed resin plate 3 and the seismic resistance and seismic isolation of the building are improved. In addition, the slits 6 provided in the foamed resin plate 3 can disperse excess pore water generated by the vibration, reduce drainage and pressure, and are very effective in preventing liquefaction of the ground. Furthermore, by winding the foamed resin disc 3 around the cast-in-place pile reinforced car 11 at the time of concrete casting, even if the soil on the wall surface of the hole 16 collapses, there is no possibility that the soil mixes with the concrete to reduce the strength of the pile. After the concrete is cast, the side wall of the pile and the wall surface of the hole 16 are in close contact with each other, so that the frictional resistance of the contact portion is increased, the pile is firmly fixed in the ground, and the support strength of the pile can be improved. .

Next, another embodiment using the pile foundation structure in the building of the present invention will be described with reference to the drawings.
FIG. 6 is a substantially partially cutaway sectional view of a pile foundation structure to which the reinforcing structure of the building of the present invention is applied.

(1) Based on FIG. 4 and FIG.
After the step (10), a reinforcement structure for the pile foundation structure of the building is provided.

(2) Excavation of the ground to be constructed in the building (excluding the reinforcing structure of the pile foundation structure of the building provided by (1)), and gravel (shown in the figure) on the floor of the excavated hole. No) is spread over the gravel and compacted with a rammer or the like.

(3) A surface pressure gauge (load cell) 21 is placed at a predetermined location on the gravel.

(4) The gravel and surface pressure gauge (load cell) 2
A foam resin board 23 is laid on the top 1 and concrete is poured from above, cured, and hardened to form a pressure-resistant board 19. At this time, a formwork is assembled between the pressure plate 19 and the pile foundation reinforcing structure 1 and the foundation 18a, and they are not joined and integrated with each other, but a space (gap).
22 are formed. Further, as the pressure-resistant panel 19,
Instead of concrete, a rigid plate-like body such as an iron plate may be used. In addition, when the foamed resin board 24 is provided integrally at the place in contact with the ground of the foundation 18a, the vibration of the earthquake or traffic is reduced by the foamed resin board 24, and the seismic resistance and seismic isolation of the building are dramatically improved. I do.

(5) A jack, a damper or the like 20 is installed at a predetermined position on the pressure-resistant board 19, and a slab 18b is installed on the jack or the damper 20 or the like.

With the above structure, the load of the building can be dispersed and supported by the pile foundation reinforcement structure 1 and the pressure plate 19, so that the load on the pile foundation reinforcement structure 1 is reduced. When the soft ground 8 under the foamed resin base 23 sinks due to an earthquake, traffic vibration, or the like, and the pressure of the surface pressure gauge (load cell) 21 decreases, the jacks, dampers 20 and the like 20 are adjusted, and By applying the pressure, the increased load of the building on the pile foundation reinforcement structure 1 can be dispersed to the pressure-resistant panel 19, and the durability of the pile foundation reinforcement structure 1 can be greatly improved.

[0035]

As described above, the foamed resin disc is wound on at least a part of the side surface of the pile body to form a surface layer. By having at least one slit along, the vibration or vibration of an earthquake or traffic is efficiently absorbed and reflected by the foamed resin board, so that the building is improved in seismic resistance and seismic isolation. In addition, groundwater generated during normal times is drained to the lower part of the pile through the slit of the foamed resin board, which is effective for ground hardening. On the other hand, if excessive pore water is generated instantaneously due to the pressure applied to the periphery of the pile during an earthquake or the like, the foam resin board is efficiently compressed and deformed due to the slit, and the foam resin board and the wall surface of the hole (soil A gap is formed between the walls, and a large amount of excess pore water can be dispersed and drained from the gap in the ground direction. This is very effective in preventing liquefaction of the ground and maintaining a stable ground. The deformation of the pile can be effectively prevented by the elasticity (spring) effect due to the deformation of the foamed resin board. Furthermore, the air layer formed in the slit can effectively block vibration or shock vibration waves generated by an earthquake, traffic, or the like. When the foamed resin board is restored after the compression deformation, the gap between the foamed resin board and the wall surface (earth wall) of the hole can be eliminated, and the support strength of the pile can be improved.

Compared with the conventional measures for reinforcing a building, it is possible to easily reinforce the structure, so that the construction period is short and the cost is economically low.

[Brief description of the drawings]

FIG. 1 shows an example in which the reinforcing structure of the present invention is applied to a pile foundation structure in a building. (A) is a vertical cross-sectional view of a part of a foundation in a building, and (b) is an X in FIG.
FIG. 4 is a schematic cross-sectional view taken along line -Y. FIG. 7C is an enlarged view of a main part B of FIG.

FIG. 2 shows another embodiment in which the reinforcing structure of the present invention is applied to a pile foundation structure in a building. (A) is a vertical cross-sectional view of a substantial part of a foundation portion of a building, and (b) is a schematic cross-sectional view taken along the line XY of (a) of FIG.

FIG. 3 is a perspective view of a foam resin board used for a pile foundation structure in the building of the present invention.

FIG. 4 is an explanatory diagram for performing construction of a pile foundation structure in the building of the present invention.

FIG. 5 is an explanatory diagram for performing construction of a pile foundation structure in the building of the present invention.

FIG. 6 is a substantially partially cutaway sectional view of a pile foundation structure to which the reinforcing structure of the building of the present invention is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pile foundation reinforcement structure 2 Pile body 3 Foam resin board 6 Slit

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 2D041 AA01 BA03 BA53 CA01 CB05 DA03 EA02 EB02 2D046 CA03 DA11

Claims (4)

[Claims] In a pile foundation structure of a building, a foam resin disc is wound on at least a part of a side surface of a pile body to form a surface layer, and a pile length is formed on an outer peripheral wall side of the foam resin disc. A pile foundation structure in a building having at least one slit along an axial direction. 2. The pile foundation structure for a building according to claim 1, wherein the slit on the outer peripheral wall side of the foamed resin board is covered with a clogging prevention body. 3. The pile foundation structure for a building according to claim 1, wherein the foamed resin disc comprises one or more of foamed polypropylene disc, cross-linked foamed polyethylene disc, foamed polycarbonate disc, and foamed polyester disc. 4. The foamed resin board has a compressive strength of 5.0 to 5.0.
Pile foundation structure in the building according to any one of claims 1 to 3 comprising using those 50.0t / m ^2.